1. Field of the Invention
This invention relates to cathode ray tubes used as pixel elements in large color displays. More particularly, the invention relates to a color pixel element cathode ray tube (CTR) having three electron beams, one for ach primary color, wherein the CRT produces a range of monolithic colors.
2. Description of Related Art
Large television display screens such as a JUMBOTRON® (registered trademark of Sony Corporation) generally use a plurality of CRTs arranged in an X and Y matrix of color pixels. Light emitting diodes may be used for smaller large display screens and rear or front protection screens may also be used, but both suffer from low contrast or brightness. CRTs are used as pixel elements in the large display screens because of the brightness and superior contrast obtainable from the matrix of these pixel CRTs. Generally, each color display pixel comprises three CRTs, one for each primary color—red, green and blue. By apportioning the intensity of each of the primary colors, a range of colors may thereby be produced. In an alternate arrangement, full color CRTs may also be assembled in a matrix to produce a large display screen. In this arrangement, raster scanning is required for each CRT. Raster scanning requires that there be a magnetic deflection yoke in addition to the other required elements of a CRT, e.g., shadow mask, primary color phosphor dots (or strips), and associated electronics. Using three CRTs per color pixel element or a plurality of color CRTs in a large display screen is costly, increases the complexity and weight, and reduces reliability of the large display screen.
There is a need for high reliability and reduced cost color CRTs that may be used as pixel elements in a large display screen.